Hi,
you need to collect the complete list of workflows, which were run on a page? I don't think, that this is possible ootb. You could iterate through the workflow archive and look there. But then note, that Adobe recommends to purge the list of completed workflows every once in a while.
In your case I would have a workflow step creating an audit entry for this page (containing the relevant information), but then you need to retain the audit entries for potentially a very long time. Or before purging the audit entries export them to a file.
Jörg